The present invention relates to a device for regulating the flow rate of air flowing in a rotary shaft of a turbomachine, and in particular in a compressor shaft of such a turbomachine.
In a turbomachine, it is common practice to take air for various purposes, in particular to regulate the pressurization of oil enclosures so as to prevent oil leaks, or to cool certain parts of the turbomachine.
The functions of pressurizing and cooling these portions of the turbomachine are performed by taking air that normally comes from the high and low pressure compressors of the turbomachine, with the choice depending on the temperature and pressure conditions desired for the air that is taken. Air as taken in this way generally passes inside the shafts of the compressor or the turbine so as to be delivered to the oil enclosures for pressurizing or to the components of the turbomachine that need cooling.
The taking of air from the high and low pressure compressors thus depends on the speed of rotation of the shaft driving those compressors. For pressurizing oil enclosures, it becomes necessary, at low speeds, to take air that is highly compressed in order to ensure good sealing of the oil enclosures.
However, taking highly compressed air at high speed is harmful for the lifetimes of sealing systems. It can lead to certain sensitive parts of the turbomachine being heated excessively, and that is penalizing in terms of performance.
European patent No. 0 698 739 B1 discloses a device for taking air that comprises a toroidal shell placed in a wall that is swept by a flow of air, the shell being suitable for pivoting about an axis to go from a position in which it projects maximally from the wall to a position in which it is retracted in the wall. Nevertheless, that device does not enable the flow rate of the air that is taken to be regulated as a function of the requirements for air.